Third generation partnership project (3GPP) and Long Term Evolution (LTE) mobile telecommunication systems provide high data rate, lower latency and improved system performances. However, such systems are optimized for regular data communications. Normally there is no need for repeatedly retransmissions. Therefore, in the current mobile network system the starting subframes of uplink or downlink data channels are well defined.
As the applications on mobile networks evolve, the above assumptions for the starting subframes of the data channel may not be true. For example, machine-to-machine (M2M) applications required low-cost devices and improved coverage other than current cellular communication system. For example, some smart-metering deceives suffer a significantly larger path-loss (e.g., 20 dB path loss) than that in the typical operation condition of normal devices, which are often installed in the basements of residential buildings or locations shielded by foil-backed insulation, metalized windows, or traditional thick-walled building construction. In order to serve these devices, 3GPP RANI working group have studied for coverage improvement and cost reduction for these MTC devices in coverage-hole scenario. Some potential solutions have been identified such as repetition of the physical channels to improve the coverage. In addition, cost reduction techniques are studied, including reducing the data buffer size and operation bandwidth, reducing receiving the antenna number and so on. With repetition of most of the physical channels, there may be misunderstanding between base station and mobile station on the start time of the transmission of some physical channels. Therefore, it is important to have a method to determine the start subframe of the physical channels. The benefit of determining the start subframe is not limited to the examples above
Improvements and enhancements are required for UE to determine the start subframe of the physical channels.